This protocol outlines methods of isolating and characterizing relatively purified antigens from a variety of Aspergillus species and their employment in procedures which will detect the primary interaction between such antigens and circulating antibodies. Such a test system depends only on the primary antigen-antibody interaction, the first step in a series of biologic processes which may or may not subsequently result in a secondary or tertiary manifestation. Both qualitative (e.g. radioimmunodiffusion, radioimmunoelectrophoresis and direct and indirect immunofluorescence) and quantitative primary binding tests (e.g. ammonium sulfate test, co-precipitation test) will be employed. Following the determination of a standardized primary antigen-antibody interaction by either of the quantitative techniques mentioned, inhibition studies will be performed to evaluate the antigenic similarities and/or differences of related and unrelated strains of fungi and bacteria. The genus Aspergillus will be used as the initial model because of the wide spectrum of clinical disease induced by this organism. Subsequently, antigenic components similarly derived from other fungi will be investigated by application of similar methods. While stressing the development of primary binding systems to accurately measure and define the classes of antibody populations involved, existing secondary (precipitation in gel and/or solution, hemagglutination, etc.) and tertiary tests (e.g. dermal responsiveness) will also be employed to better understand the efficiencies of these antibody populations. Since host response to a given antigenic stimulus very frequently is a function of both humoral and cellular immune mechanisms, the isolated antigenic components will be employed to investigate cellular immune responsiveness and its relationship to both humoral activity and total host immunity. Both dermal reactivity and lymphocyte stimulation by these components as measured by the incorporation of tritiated thymidine into the DNA of lymphocytes will be employed to this end.